Siemens SINUMERIK 840D sl Function Manual page 210

M3: Coupled axes
5.1 Coupled motion
This allows the speed to be changed for the independent motion of a coupled motion axis
using a feed override or a DRF offset to be defined using the handwheel in AUTOMATIC and
MDA modes.
Dependent coupled motion axis
With respect to the motion of a coupled motion axis, which is dependent on the leading axis,
only the coupled-motion axis interface signals that effect termination of the motion (e.g. axis-
specific feed stop, axis inhibit, control system enable, etc.) are effective.
Leading axis
When a coupled axis grouping is active, the interface signals (IS) of the leading axis are
applied to the appropriate coupled motion axis via the axis coupling, i.e.
• A position offset or feed control action of the leading axis is applied via the coupling factor
to effect an appropriate position offset or feed control action in the coupled motion axis.
• Shutdown of the leading axis as the result of an interface signal (e.g. axis-specific feed
stop, axis inhibit, servo enable, etc.) causes the corresponding coupled motion axis to shut
down.
Position measuring system 1/2 (DB31, ... DBX1.5/1.6))
Switch-over of the position measuring system for the leading and coupled motion axes is not
inhibited for an active coupled axis grouping. The coupling is not canceled.
Recommendation: Switch-over the measuring system when the coupling is deactivated.
Tracking (DB31, ... DBX1.4)
Activation of tracking for an axis is done via the PLC program by setting the following NC/PLC
interface signals:
DB31, ... DBX2.1 = 0 (control system enable)
DB31, ... DBX1.4 == 1 (tracking mode)
When activating tracking mode for a coupled axis grouping, the specified NC/PLC interface
signals must be set simultaneously for all axes (master and slave axes) of the coupled axis
group.
If tracking mode is activated for the master axis only, a permanent offset results within the
coupling.
Whether and which axis is a leading or a following axis can be seen from the following NC/
PLC interface signals and system variables:
DB31, ... DBX99.0 (leading axis/spindel active)
DB31, ... DBX99.1 (following axis/spindel active)
$AA_COUP_ACT[axis identifier] (see: Status of coupling)
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Function Manual, 09/2011, 6FC5397-2BP40-2BA0
Special Functions